Structure and vibrational spectra of MIIAIVB3VI-type crystalline and glassy semiconductors

Abstract The crystal structure PbGeS3 and SnGeS3 compounds consists of infinite chains of top-sharing [GeS4] tetrahedra. These chains are ‘laced’ together by chains of ψ-octahedra coordinating the lead (tin) atoms. The vibrational spectra of ordered and disordered phases of PbGeS3 and SnGeS3 in the range of symmetric vibration A1 were studied taking into account the crystalline structure. The factors determining the peculiarities of the vibrational spectrum have been discussed. The role of the [GeS4] tetrahedra as universal structural units in the formation of the vibrational spectra of crystalline and glassy tin and lead thiogermanates is noted. On the basis of the similarity of vibrational spectra it was concluded that the glasses in Ge2S3–SnGeS3–PbGeS3 series are isostructural.